• This is nothing but a fortuitous encounter with my old roommate of 30 years ago, whom I hadn't seen since graduation.

Nowadays, it is frequently used in contexts where the chance event described has a fortunate outcome. An extended meaning lucky used in English at least since the 1920s is controversial. Substitute fortunate for fortuitous when the meaning is lucky:

• In a fortunate [not fortuitous] turn of events, the lost package was found and handed in by a passer-by.